Various information protection techniques are being developed to protect digital media that can be easily copied or modified.
Among the techniques, information hiding as well as encoding is being widely used to assure confidentiality. According to this information hiding technique, a digital medium can be modified, and data can be embedded into the digital medium.
In this regard, Korean Patent Application Publication No. 10-2007-0076130 (Title of Invention: “Information Embedding and Extracting Method for Image Authentication”) describes a lossless data embedding method, which does not cause a loss of original data during processes of embedding and extracting information; according to the method, an image is divided into a multiple number of blocks, each of the divided blocks is divided into sub-blocks, and authentication information is embedded into one pixel of each of the sub-blocks, wherein the authentication information (binary information) is inserted into a pixel having a minimum pixel value.
However, there has been a limit since it is not easy to reversibly hide information in a compressed image, and not an original image, as a random number output is generated when an image is compressed.